The objective of this proposal is to continue the elucidation of the interacting control mechanisms operative between monoamines and amino acid metabolism which may involve the metabolism of the Krebs cycles associated with these amino acids. In vivo and in vitro preparations of animal brain and sympathetic ganglia will be treated with drugs which affect serotonin (e.g., p- chloroamphetamine, tryptophan) or catecholamines, (e.g., amphetamine, chloropromazine, gamma methyl tryosine). Double-labeling experiments with C14-glucose and H3-acetate will be utilized to follow the turnover rate of glutamate, glutamine, aspartate, GABA and the Krebs cycle. In rain preparations, discrete areas such as cerebral cortex, cerebellum, brain stem and caudate nucleus will be studied. The effect of inhibitors of amino acid metabolism (e.g., alpha-fluoroglutarate, dipropyl acetic acid, aminooxyacetic acid) or of GABA transmission (bicuculline) on formation of catecholamine from H3-tyrosine will be investigated in tissue slices and synaptosomal preparations. Correlations will be made of the turnover rates and levels of amino acids and monoamines.